Just want to chime in with my experience and opinion...
I've gone to WDW the first week of December (week AFTER Thanksgiving) in 2000, 2001 and 2003 (and hopefully 2005!) and it was very low crowds and shorter hours. MK always closes 6:00p on MVMCP nights and 7:00p on non-MK nights and to me that is NOT peak season hours!!!! On my trip this past August MK closed at 8:30p - 9:30p most nights and then 10:30p - 11:00p on Saturdays. To me you could argue that those might be peak season hours compared to the first couple of week in December.
The week AFTER Thanksgiving thru the week BEFORE Xmas are NOT peak season, they are VALUE season. The hours are shorter than Summer, School vacations, Thanksgiving week, Christmas week, Easter, July 4 week etc...
I have a feeling some are getting the first couple of weeks of December's crowds and hours confused with Xmas Week thru New Year's. They are quite different!
Also, it is true that the first 2 weeks of December are very popular with DVCers and that's because it is value season so it's cheaper and it's also a festive time to go, but it still doesn't affect the overall crowds the at WDW for the BEGINNING of December.
If you look at any website that has historical Disney hours for the first part of December, it becomes quite clear that Disney does not consider it peak season but off season and here's just one year's example:
December 2003
Magic Kingdom
December 1 -- 9:00 a.m. - 7:00 p.m.
December 2 -- 9:00 a.m. - 6:00 p.m.
December 3 -- 9:00 a.m. - 7:00 p.m.
December 4,5 -- 9:00 a.m. - 6:00 p.m.
December 6 -- 9:00 a.m. - 11:00 p.m. (Sat)
December 7 -- 9:00 a.m. - 6:00 p.m.
December 8 -- 9:00 a.m. - 7:00 p.m.
December 9 -- 9:00 a.m. - 6:00 p.m.
December 10 -- 9:00 a.m. - 7:00 p.m.
December 11, 12 -- 9:00 a.m. - 6:00 p.m.
December 13 -- 9:00 a.m. - 10:00 p.m. (Sat)
December 14 -- 9:00 a.m. - 6:00 p.m.
December 15 -- 9:00 a.m. - 7:00 p.m.
December 16 -- 9:00 a.m. - 6:00 p.m.
December 17 -- 9:00 a.m. - 7:00 p.m.
December 18,19 -- 9:00 a.m. - 6:00 p.m.
December 20,21 -- 9:00 a.m. - 10:00 p.m. (Sat)
December 22 -- 9:00 a.m. - 11:00 p.m.
December 23,24 -- 9:00 a.m. - 10:00 p.m.
December 25-31 -- 9:00 a.m. - 12:00 a.m.
As you can see most days in December, MK closed at 6:00p or 7:00p unless it was Saturday night. That's PEAK hours??? I don't think so. Then the bolded hours are Christmas week thru New Year's; quite different hours, don't ya think? IMHO.